1. Technical Field
The present invention relates to a liquid crystal display device having an illumination device including a light guide plate and a light source, an electronic apparatus including the liquid crystal display device, and the illumination device.
2. Related Art
A liquid crystal display device including a transmissive liquid crystal panel has an illumination device 1008 in which a light source 1890 is arranged in a light incident portion 1080a composed of a side end face extending in an X-axis direction, for example, as shown in FIGS. 14A and 14B, on a light guide plate 1080, and the liquid crystal panel is arranged so as to be stacked on a light-emitting surface 1080b side of the light guide plate 1080. With regard to illumination devices such as illumination device 1008, a configuration in which a plurality of grooves 1086 running in a longitudinal direction in the x-axis direction, that is the direction in which the light incident portion 1080a extends, are formed on a bottom surface 1080c facing the light-emitting surface 1080b on the light guide plate 1080, has been proposed so as to increase the emission intensity of the illumination light (see, JP-A-2008-20888).
In the illumination device 1008 having the above described configuration, light emitted from the light source 1890 is incident to the inside of the light guide plate 1080 from the light incident portion 1080a as shown by arrow L11, and then advances through the inside of the light guide plate 1080 while repeating total reflection inside the light guide plate 1080. Next, as shown by arrow L12, the light is reflected and diffused on a side surface 1867 of the groove 1086 extending parallel to the X-axis direction, and therefore the illumination light is emitted from the light-emitting surface 1080b as shown by arrow L13. When this happens, light reflected in both end portions 1868 and 1869 in the X-axis direction on the groove 1086 advances in a variety of directions, thereby enhancing uniformity of the illumination light emitted from the light-emitting surface 1080b of the light guide plate 1080.
However, as in JP-A-2008-20888, in the case in which the groove 1086 is provided running in the longitudinal direction in the X-axis direction (the direction in which the light incident portion 1080a extends), the side surface 1867 of the groove 1086 crosses a direction in which light advances inside the light guide plate 1080, and therefore, an optical component advancing in a Y-axis direction inside the light guide plate 1080 is excessively reduced by the groove 1086. For this reason, there is a problem in that, in the illumination light emitted from the light guide plate 1080, the intensity of the illumination light near the light incident portion 1080a becomes too strong, and the intensity of the illumination light at a position a distance from the light incident portion 1080a is reduced by that amount. In order to solve the problem, a configuration in which the density of the grooves 1086 in a region close to the light incident portion 1080a is made different to the density in a region spaced apart from the light incident portion 1080a is conceivable; however, in a case in which the light guide plate 1080 is enlarged accompanying enlargement of the liquid crystal panel, adjustment of the density of the grooves 1086 does not solve the above described problem.
In addition, in the liquid crystal display device, a local dimming method in which the light source 1890 is divided into a plurality of blocks along the X-axis direction, and an emission amount of the light source 1890 is controlled for each block so as to improve contrast and relieve residual images and the like is adopted. In this case, when adopting the illumination device 1008 shown in FIGS. 14A and 14B, the light is reflected and diffused on the side surface 1867 of the groove 1086 and in both the end portions 1868 and 1869 in the X-axis direction, and therefore, leakage of light to the adjacent region is excessive, resulting in a reduction in the effect of adopting the local dimming method.